I'd like to move onto some other things, including a couple of very important court cases where judgments have issued this week - the case on gene patents in the US, and the Simon Singh libel case in the UK.
But one loose end from all the debate about Sam Harris was whether we are setting the bar too high by maintaining the "is/ought" distinction.
My answer is, "No." Hume pointed out that no number of propositions that use the copula "is" can ever logically entail a proposition with the copula "ought". Yet, he says, we often see philosophers slip into "ought" conclusions without ever explaining how they did it. That's a shrewd observation, and we should not throw it out in the name of being able to study morality more easily. It imposes a discipline on us, that if we start introducing "oughts" we must explain how we did it, and it can't simply be a logical entailment from a string of "is" statements.
Hume's own approach is to connect "ought" with human psychology - he tends to speak of desires, but he means this in a broad sense. Today, we should talk, with some vagueness, about desires, values (or maybe this should be valuings), fears, hopes, sympathies, etc. This is a place where the "etc." is okay, because it is possible in principle to sort out the detail of how all these things relate to each other, though it's difficult to get precisely right in practice. These aspects of human psychology connect up with facts about the world to give us reasons, or rational motivations, or "oughts". For example, if I desire the amelioration of suffering, I am rationally motivated, other things being equal, to give money to certain charities (if they will be effective), or to interfere (if I'm likely to be effective) to stop a bully beating up someone smaller.
There are other ways to try to derive "oughts": e.g. the will or purposes of a God, some process of souped-up Reason; some kind of non-natural, metaphysical properties of things. In my view, none of these work. (Note that the Euthyphro problem remains even if we invoke the will of God or the gods.)
We are left with a world in which "oughts" ultimately depend on features of human psychology (plus facts about what will be effective). Since I can't see what else they could ultimately depend on, I'm not too embarrassed by this, but I do concede that there is this psychological craving to find a basis outside of human psychology, i.e. an external or "objective" basis. Even I can get myself in a mood where I feel this. It's the creepy feeling of not wanting to deny that torturing babies is not just really wrong ... but really, really wrong.
But that external basis doesn't exist. Therefore, morality is not objective: it is not grounded solely in something external to our psychological makeup. Since our psychological makeup is not identical from person to person, this leaves room for some indeterminacy, but perhaps not all that much if we can agree on all the non-moral facts. The more we agree on the facts, the more we tend to converge on agreement about what should be done.
Morality is, however, non-arbitrary: it is grounded in widespread human values, sympathies, desires, needs, etc., combined with facts about the world.
You might think that "needs" are objective, but even what counts as a need has some subjective element to it; survival itself is not important because of some external thing such as the will of a god, but your survival is important to you and to those who love you or depend on you. Even what counts as your flourishing has some subjective element; it will depend on what you value, or on what another person making judgments about your flourishing (or otherwise) values. I can't see any prospect of a plausible concept of flourishing that is not value-laden (laden with the values of somebody) to some extent.
The elements of human psychology that I've mentioned - desires, sympathies, fears, and so on can give us reasons to act in ways that are not narrowly selfish, e.g. if we want to be able to enjoy loving relationships, live in peaceful societies, or ameliorate some of the immense suffering in the world. They can give us reasons to favour certain laws, to support entire systems of social or legal norms that govern conduct, or to try to inculcate certain dispositions into children. We have many reasons to act in ways that are not narrowly or short-sightedly self-interested. Importantly, our desires, sympathies, fears, and so on can give us reasons to try to dismantle moral systems that fail to advance such things as human happiness (which almost all of us value) and which actually operate cruelly.
All of this can be examined objectively, in the sense of carefully, disinterestedly, attempting to get at the truth rather than to confirm our biases, without throwing away Hume's point. In fact, Hume's point is a fundamental finding that we ought(!) to work with if we wish to make progress in the study of morality.